.active{
    color:blue
}
.nav_out{
    overflow: hidden;
}
.nav{
    width: 60px;
    height: 40px;
    text-align: center;
    line-height: 40px;
    float: left;
    background: #ccc;
}

.list{
    width: 1000px;
    overflow: hidden;
    margin-top: 15px;
}

.unit{
    width: 200px;
    float: left;
    margin: 15px;
}

.gray{
    background: #ccc;
    color: black;
}

.blue{
    background: skyblue;
    color: #fff;
}